<template>
  <div class="todo-footer" v-show="total">
    <label>
      <!-- <input type="checkbox" :checked="isAll" @click="checkAll" /> -->
      <!-- // 替代上面的方法 -->
      <input type="checkbox" v-model="isAll" />
      <span>
        <span>已完成{{ completed }} </span> / 全部 {{ total }}
      </span>
      <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
    </label>
  </div>
</template>

<script>
export default {
  name: "MyFooter",
  props: ["todos"],
  methods: {
    // checkAll(e) {
    //   console.log(e.target.checked);
    //   this.checkAllTodo(e.target.checked);
    // },

    // 清空所有已完成
    clearAll() {
      if (confirm("是否清除所有已完成？")) {
        // this.clearAllTodo();
        this.$emit("clearAllTodo");
      }
    },
  },
  computed: {
    // computed 中默认方法调用的get读取方法，不能设置该值；如果需要修改该值，需要实现set方法
    isAll: {
      get() {
        return this.completed === this.total && this.total > 0;
      },
      set(value) {
        // if (value) {
        //   this.todos.forEach((element) => {
        //     element.done = true;
        //   });
        // } else {
        //   this.todos.forEach((element) => {
        //     element.done = false;
        //   });
        // }

        // this.checkAllTodo(value);
        // 修改成通过$emit(自定义事件名,value)触发
        this.$emit("checkAllTodo", value);
      },
      // return this.completed === this.total && this.total > 0;
    },
    total() {
      return this.todos.length;
    },
    completed() {
      // let sum = 0;
      // this.todos.forEach((element) => {
      //   if (element.done) {
      //     sum = sum + 1;
      //   }
      // });
      // return sum;
      // let total = this.todos.reduce((previous, current) => {
      //   return previous + (current.done ? 1 : 0);
      // }, 0);
      // return total;
      return this.todos.reduce((prev, curr) => prev + (curr.done ? 1 : 0), 0);
    },
  },
};
</script>

<style scoped>
/** footer */
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}
.todo-footer label {
  /* display: inline-block; */
  margin-right: 20px;
  cursor: pointer;
}
.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}
.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>
